The present invention relates to a communication system and to a semiconductor device. For example, the present invention relates to a technology for issuing an emergency notification with a frame compliant with the Ethernet (registered trademark) standard.
A technology described, for instance, in Japanese Unexamined Patent Application Publication No. 2006-67038 reduces a delay in the transmission of an emergency frame. If an emergency frame is encountered during the transmission of a normal frame, the currently transmitted normal frame is interrupted and discarded to transmit the emergency frame.